A Publication of the Delta Stewardship Council

We Are Not Alone - Water Scarcity a Worldwide Problem

Water Use Per Person Per Day in California by County in 2000

A breakdown of water usage in gallons per person per day(GPD) in California in the year 2000, by a sampling of counties shows a wide range:

San Francisco County

108 GPD

Santa Cruz County

121 GPD

Sonoma County

161 GPD

San Diego County

184 GPD

Orange County

190 GPD

Sacramento County

261 GPD

Riverside County

294 GPD

Yolo County

299 GPD

Stanislaus County

321 GPD

Mono County

471 GPD

These figures, taken from a sacbee.com interactive map of water use per capita in California, show water usage from public water supply, minus use for industry and irrigation, divided by the population taking public water.

Rising water demands and scarcity are a worldwide problem-not simply a California one. Regions in Europe’s Mediterranean basin and Australia are among the world areas suffering from irregular water supply and rising water demands.

CALFED Lead Scientist Cliff Dahm recently traveled to Girona, Spain, where experts from around the world gathered to share their views and to suggest strategies at a conference titled “Water Scarcity and Management under Mediterranean Climate.”

Mediterranean climates, such as we have in much of California, present significant water resource challenges worldwide, Dahm said. People living in Mediterranean climates wrestle with the reality of providing water for human use and protecting valuable aquatic ecosystems. Conservation, new water supplies from wastewater reuse and desalinization, as well as groundwater usage, play key and increasing roles in maintaining water availability during dry periods.

Worldwide, Mediterranean climates are defined by cool, wet winters and warm, dry summers. These climates have a distinctive dry period - often punctuated by drought - when water demand for agriculture and urban areas is high. As a result, surface storage of water from wetter periods for later use (reservoirs), use of groundwater, and use of alternative water supplies, such as treated wastewater and desalinization of brackish water or sea water, are necessary.

Mediterranean climate areas also have a dry season that coincides with the potential highest water demand by humans, animals and crops. Population and economic growth may severely strain water managers’ ability to meet future water demand in these areas.

Richer countries with Mediterranean climates, such as those in Europe, Australia, and the U.S., invest in the infrastructure (dams, groundwater wells, water transfer systems, wastewater treatments, and desalinization) to meet their water needs. Yet, even these expensive systems can be overwhelmed in times of serious drought, Dahm said. As populations grow and serious droughts occur, more expensive technologies like wastewater reuse and desalinization are being increasingly looked to as solutions. The wealthier countries also are looking to power these alternative water producing technologies with renewable energy supplies. Energy and water supply are intimately linked in all these countries with Mediterranean climates.

One suggestion from the conference was for the need for flexible water quality standards during drought. High levels of nitrate, ammonium and phosphate during periods of drought are found to increase algal blooms and alter foodwebs downstream of wastewater treatment plants. Water quality standards should be more stringent during drought in Mediterranean climates.

“…after a seven-year drought that brought reservoirs down to 15 percent capacity in Southeast Queensland, water restrictions reduced individual use from 106 gallons per person per day, to 37 gallons per person per day.”

-- Cliff Dahm, CALFED Lead Scientist

At the conference, Dahm shared his experience working in other parts of the world on complicated water issues similar to those facing the Mediterranean and Australia. In the latter, he said that after a seven-year drought that brought reservoirs down to 15 percent capacity in Southeast Queensland, water restrictions reduced individual use from 106 gallons per person per day, to 37 gallons per person per day. Restrictions applied to pools, lawns, landscaping and other urban use. Inside their homes, for instance, residents learned to take four-minute showers, and to use unused ice cubes and buckets of graywater (wastewater) from showers to water plants. Queensland’s present goal is to target per capita water usage to 45 gallons a day. This compares to average daily per capita water use in the U.S. of between 100-150 gallons and in California of more than 230 gallons. California’s 20 percent reduction by the 2020 target date would amount to approximately 185 gallons a day. (See sidebar for a breakdown of water usage per person per day in California in a sampling of counties).